staggering on acceleration

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tucsonsean

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Now that the clutch is behaving, I'm working towards going through emissions. It's an '85 2M4 that runs fine, doesn't leak, and doesn't smoke. But it staggers and is initially unresponsive from a standing start. Acceleration after that is fine. Where should I start? Can anyone suggest a protocol for sorting this out? Thanks.
 
You have to do emissions? I don't have to worry about them here.
 
Plugs, wires, cap and rotor would be my first inspect list. the weak low end could be caused by a weak spark. also, check the timing. short terminals A & B of the diagnostics plug, (next to the lighter, under the plastic panel) timing should be at 8 BTDC. I also have an 85 2M4 SE. runs great but idles high-around 1400 warm. haven't figured that one out yet. If anyone has sugggestions, I'm listening...
 
Every year. Every vehicle. Pima County (AZ) has a strong committment to improving air quality.

But my issue right now is this hesitation from a standing start. It's only from a standing start, both when cold or warmed up.
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In a past life, when cars had carburetors, starting line bog was due to either too much fuel or too little- I forget which- I'm old, but that's where your problem is. What happens when you accelerate very slowly, better?
 
Currently, I can't accelerate slowly. It'll bog down if I try to feather it, then when the pedal is depressed a certain distance, it just jumps. If I raise the rpms before releasing the clutch, it'll still stagger before it takes off.

It has a new ignition module, but I haven't checked the plugs yet. I thought the TBI would be easier than the dual Strombergs on my old English cars. The fuel filter seems like a good start, and I'll change the O2 sensor.
 
tucsonsean said:
Currently, I can't accelerate slowly. It'll bog down if I try to feather it, then when the pedal is depressed a certain distance, it just jumps. If I raise the rpms before releasing the clutch, it'll still stagger before it takes off.

It has a new ignition module, but I haven't checked the plugs yet. I thought the TBI would be easier than the dual Strombergs on my old English cars. The fuel filter seems like a good start, and I'll change the O2 sensor.
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OH! i think i know. I picked up mine recently and at one point i wouldn't be able to lightly gas it or it would die out. I replaced fan switch sensor or something (looks luck a nut on the block below thermostat pipe) It fixed that problem because it controls fuel. Also could be 02.
 
Staggering off the line and such could be a lot of things.
First do a tune up and have the fuel injector cleaned. If the injector is a little dirty it may be spitting a little causing the stumble at low throttle. Next check all vacuum lines for a tight fit and no cracks. The TPS sensor could also have a "dead" spot in it as well. This tells the computer where the throttle is at. Over time they can develop a dead spot causing the computer to think you are flooring it. So it tries to increase fuel and the stumble. You can test this by removing the connector and putting an ohm meter across the two terminals. If I recall it should go be between 100 ohms and 0 ohms and move smoothly between as the throttle is moved from closed to open. It the resistance jumps at one spot, that is the dead spot and the TPS needs to be replaced.

Bird59 - High idle can be a vacuum leak or a dirty IAC.
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Oreif to the rescue--again. Thanks, O. Gives me some structured approach. Do I have to remove the injector to clean it. Maybe a stupid question, but I really don't know. But it does feel the way a carburetor would sometimes 'load up' on acceleration if the mix was wrong.
 
Ok. Turned out to be a code 34 (map sensor). Apparently, the ecm uses data from this sensor to set the tps--or falls back on standard data.
 
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